To a degree that may be appreciated or estimated; perceptibly; by a difference that may be remarked; noticeably: as, he is appreciably better.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
ad. to a noticeable degree
Word Usage
"Saying the "size or nature" of the insurgency hasn't changed appreciably is another way of saying Bush is completely failing in his attempt to attack and weaken the insurgency."